Sutter M L, Loftus W C
Center for Neuroscience, University of California, Davis, California 95616, USA.
J Neurophysiol. 2003 Oct;90(4):2629-47. doi: 10.1152/jn.00722.2002. Epub 2003 Jun 11.
The intensity tuning of excitatory and suppressive domain frequency response areas was investigated in 230 cat primary auditory cortical and 92 posterior auditory field neurons. Suppressive domains were explored using simultaneous 2-tone stimulation with one tone at the best excitatory frequency. The intensity tuning of excitatory and suppressive domains was negatively correlated, supporting the hypothesis that inhibitory sidebands are related to excitatory domain intensity tuning. To further test this hypothesis, we compared the slopes of the edges of suppressive bands to the intensity tuning of excitatory domains. Edges of suppressive bands next to excitatory domains had slopes significantly more slanted toward the excitatory area in neurons with intensity-tuned excitatory domains. This relationship was not observed for suppressive band edges not next to the excitatory domain (e.g., the lower edge of lower suppressive bands). This indicates that intensity tuning ultimately observed in the excitatory domain results from overlapping excitatory and inhibitory inputs. In combination with results using forward masking, our results suggest that there are separate early and late sources of inhibition contributing to cortical frequency response areas, and only the early-stage inhibition contributes to excitatory domain intensity tuning.
在230只猫的初级听觉皮层神经元和92只后听觉场神经元中，研究了兴奋性和抑制性区域频率响应区域的强度调谐。使用在最佳兴奋性频率下的一个音调与另一个音调同时进行双音刺激来探索抑制性区域。兴奋性和抑制性区域的强度调谐呈负相关，这支持了抑制性边带与兴奋性区域强度调谐相关的假设。为了进一步检验这一假设，我们将抑制带边缘的斜率与兴奋性区域的强度调谐进行了比较。在具有强度调谐兴奋性区域的神经元中，紧邻兴奋性区域的抑制带边缘的斜率明显更倾向于兴奋性区域。对于不紧邻兴奋性区域的抑制带边缘（如下抑制带的下边缘），未观察到这种关系。这表明在兴奋性区域最终观察到的强度调谐是兴奋性和抑制性输入重叠的结果。结合使用前向掩蔽的结果，我们的结果表明，存在单独的早期和晚期抑制源对皮层频率响应区域有贡献，并且只有早期抑制对兴奋性区域强度调谐有贡献。
